Was Titanic's ship's time aligned with longitude time of noon position?

[Markus Philipp]

Several debates have taken place about Titanic's ship's time, especially whether clocks were set back 23 minutes before collision or not. This question should not be discussed in this thread, there are mininum 2 other threads on this board availabe.

I want to put up for discussion whether the ship's time was aligned with longitude time of her noon position.
Some testimonies are suitable to create doubt:

3rd Officer Lightoller said to Senator Smith, that Titanic disappeared at 2.20 ship's time. The clocks were not set back, because they had something else to think off. His watch was adjusted to ship's time of midnight Saturday.
2nd officer Lightoller joined in to give give supplementary information:
Mr. PITMAN. They are corrected in the forenoon, perhaps half a minute or a minute; that is all.
Senator SMITH. What is that, Mr. Lightoller?
Mr. LIGHTOLLER. The clocks are set at midnight, but that is for the approximate noon position of the following day. Therefore Sunday noon the clocks will be accurate.
Senator SMITH. That is Mr. Lightoller, the second officer. (To the witness What was the Greenwich time compared with the ship's time?
Mr. PITMAN. I can not say.
Senator SMITH. Can you say, Mr. Lightoller?
Mr. LIGHTOLLER. I can give you the Greenwich time.
Senator SMITH. I wish you would.
Mr. LIGHTOLLER. 5.47 - 2.20 - 5.47 Greenwich mean time: 2.20 apparent time of ship.
5.47 GMT corresponds with 0.47 NYT. That would mean that ship's time was 1h 33 minutes fast of EST.
Lightoller beeing asked about his duty times said:
16838. You would have finished your morning watch by then? - I should.
16839. And you would be off duty? - Yes. I may incidentally mention the fact that I should be on the bridge between a quarter to 12 and a minute or two past 12 taking the noon position; I should be there with the Commander and the Chief and First Officers.

Marconi operator Harold Bride said:
Senator SMITH. Did you have a watch or clock in your room?
Mr. BRIDE. We had two clocks, sir.
Senator SMITH. Were they both running?
Mr. BRIDE. Yes, sir; one was keeping New York time and the other was keeping ship's time.
Senator FLETCHER. The difference was about 1 hour and 55 minutes?
Mr. BRIDE. There was about 2 hours difference between the two.
.....

It is possible to reconstruct Titanic's noon position and therewith ship's time for this longitude.
Based on the evidence of 5th officer Lowe Titanic's position at Sunday noon was 126 miles before the corner. The course was south 60,5° west.
The noon position is calculated to 43°02' North and 44°31' West.
The correct ship's time for this longitude would be 2 hours 2 minutes fast of EST.

To summarize the evidences above:
Ship's time derived from noon position: 2 h 2 minutes fast of EST.
Bride: 1 h 55 minutes fast of EST.
--conclusion: ship's time was not corrected in the forenoon as stated by Pitman.
Pitman: Clocks were not set back, but
Lightoller said: 5.47 - 2.20 - 5.47 Greenwich mean time: 2.20 apparent time of ship.
--ship's time 1 h 33 minutes fast of EST.
Supposed this 1 h 33 minutes was the result of a clock set back which according to Pitman did not take place the ship's time before Alteration would be 1 h 33 minutes + 23 minutes equaling 1 h 56 minutes. At least this is nearly consistent with 1 h 55 which we got from Bride. Unfortunately this 1 h 55 minutes was proposed by Senator Smith, Bride just confirmed "about two hours".

There is a difference of 6 or 7 minutes between correct longitude time and the time which we can derive from Bride and Lightoller. When we allow an uncertainty of one knot the noon position found next day may be 25 miles before of after the one precalculated. Half a longitude corresponds with 2 minutes, so the difference should not exceed 2 minutes, but we find a difference of 6 or 7 minutes.

Now my first question I want to ask to those who are familiar with astronomical navigation:
If really ship's time at Sunday April 14 was just 1 h 55 instead of 2 h 2 min fast of EST, the navigators would have observed the zenith of the sun at 11.53 ship's time. Luckily the time equation, the difference between mean and true longitude time was only a few seconds at April 14, so we can leave that aside.
11.53 happens to be in the middle of the interval given by Lightoller, a quarter to 12 and 2 minutes after 12.

When navigators take noon observations, do they stop their takes as soon as they have found the zenith,
or do they take some points after the zenith as well to have some couples of points before and after the zenith?

 

[Samuel Halpern]

3rd Officer Lightoller said to Senator Smith, that Titanic disappeared at 2.20 ship's time.

I believe you meant 3rd Officer Pitman.

Ship's time derived from noon position: 2 h 2 minutes fast of EST.
Bride: 1 h 55 minutes fast of EST. --conclusion: ship's time was not corrected in the forenoon as stated by Pitman.

Markus, I believe you are not correctly interpreting what Bride was saying. It was Sen. Fletcher who asked if the two clocks differed by 1 h 55 m. Two days before that (Day 8 of the American inquiry), Fletcher heard Cyril Evans, the wireless operator from Californian, state:
"Mr. EVANS. (interposing). At 11 o'clock, approximately; 9.05 New York time."
thus suggesting that Californian was 1h 55m ahead of NY time. That is where Fletcher came up with this specific time difference. Harold Bride was not agreeing with him, he was correcting him when he said that, "There was about 2 hours difference between the two."

 

[Jim Currie]

Evans specific ally stated that Californain was 1 hour 55 minutes FAST of EST New York but his captain said the Californian was 1 hour 50 minutes FAST of EST New York. Hos captain was correct. otherwise the Noon Longituide of Californian would have been 46-15 West and that was absurd.

 

[Markus Philipp]

Evans specifically stated that Californain was 1 hour 55 minutes FAST of EST New York but his captain said the Californian was 1 hour 50 minutes FAST of EST New York. Hos captain was correct. otherwise the Noon Longituide of Californian would have been 46-15 West and that was absurd.

May be there is a simple explanation for that five minutes difference:
Senator SMITH. When did you next communicate with the Titanic and what was the message you sent or received?
Mr. EVANS. 9.05 New York time, sir.
Senator SMITH. What day?
Mr. EVANS. On the 14th, sir, the same evening, New York time, that is. I went outside of my room just before that, about five minutes before that and we were stopped, and I went to the captain and I asked him if there was anything the matter. The captain told me he was going to stop because of the ice, and the captain asked me if I had any boats, and I said the Titanic. He said "Better advise him we are surrounded by ice and stopped." So I went to my cabin, and at 9.05 New York time I called him up. I said "Say, old man, ...
At 10.50 respectively 9.00 he spoke to his captain. Simply some minutes elapsed between speaking to his captain and sending this message.
So I have good confidence that 1.50 is correct.

Sam: I believe you meant 3rd Officer Pitman.
Of course. Sorry.

 

[Jim Currie]

I think there is probably a simple explanation.

It was the Wireless Operator's duty to change from operating using GMT to operating using EST New York. This was simply to ensure that messages received and transmitted had a common time based origin. Evans would keep the wireless room updated at specific times. If it had been Noon as is done on the bridge, then he would have used the same ship ESTNY as did Captain Lord. However, if it was his habit of adjusting his transmitting clock before retiring, then he would possibly have been advised by his ship board friend, 3rd Officer Groves. Groves was very interested in wireless telegraphy and had struck up a friendship with Evans. Groves finished work at midnight and would often visit Evans in his cabin.
At Midnight on April 13, Californian might well have been near to Longitude 46-15 West. Perhaps, since he normally went off duty after 11 pm each night, Evans waited up for Groves who advised him that at that time that the ship's clocks were 1 hour 55 minutes FAST of ESTNY?
Californian was stopped long before Evans retired. There would be unusual adjustments to be made in the clocks once the ship got underway again.

 

[Markus Philipp]

I think there is probably a simple explanation.
...
At Midnight on April 13, Californian might well have been near to Longitude 46-15 West.??? Perhaps, since he normally went off duty after 11 pm each night, Evans waited up for Groves who advised him that at that time that the ship's clocks were 1 hour 55 minutes FAST of ESTNY?
.

I am a bit confused.
Lord said in US enquiry, at 9.40 am. he was at 42-00 N 47-00 W, and at 10.21 pm. he was at 42-05 N, 50-7 W.
This works out 187 minutes of arc longitude according to 139 miles at 42° latitude.
The time elapsed is 12 hours 40 minutes. The speed is 139/12,67 = 11 knots (10.97). I exspected nothing else.
46-15 west is about 34 miles east of Corner. If Course is 240° then the distance to longitude 46-15 is just 39 miles. So Californian should have passed this longitude at somewhere 6 am and not at midnight.
Did I get something wrong?

 

[Markus Philipp]

Pitman's table and local apparent noon time.

Mr. LIGHTOLLER. The clocks are set at midnight, but that is for the approximate noon position of the following day. Therefore Sunday noon the clocks will be accurate.

3rd officer Pitman deposited a memorandum for US-enquiry board with regard to daily mileages, speed and clock alterations. The mileages are correct, but the time for clock alteration and speed for the first night look odd:

484 miles 59 minutes 20,14 knots
519 miles 44 minutes 21 knots
546 miles 44 minutes 22,1 knots

Speed during first day:
Departure at Daunt Rock: 2.20 pm.
Elapsed time til Friday noon: 21 hours 40 minutes
Clock set back: 59 minutes
Speed calculated: 484/22,67 = 21,34 knots, but 20,14 knots given in Pitman’s table.
How odd!

Based on the daily runs which can be regarded as correct one can calculate the noon longitudes.
If really it was intended to adjust the clock to LAN as Lightoller said the exspected times for clock alteration would be:

484 miles 1h 23 minutes 21 knots
519 miles 49 minutes 20,9 knots
546 miles 46 minutes 22 knots
546 miles 47 minutes 22 knots presumed
546 miles 48 minutes 22 knots presumed

Left over time to finish 5 hours total: 27 minutes

Now let’s calculate the speed for the first day with an assumed clock set back of 1 h 23 minutes:

Departure at Daunt Rock: 2.20 pm.
Elapsed time til Friday noon: 21 hours 40 minutes
Clock set back: 1 hours 23 minutes
elapsed time: 23 hours 3 minutes
Speed calculated: 484 miles / 23 hours equals 21 knots!

Thus we have 21 knots both for the first and the second day, although revolutions were increased from 70 to 72 rpm as stated by Mr. Ismay. May be, due to increasing north atlantic current from first to second day or simply changed whether conditions the ship did not speed up.

BUT:
Have a look on this evidence:

Senator FLETCHER. Had you increased the speed after leaving Southampton?
Mr. PITMAN. After we left Queenstown we had.
Senator FLETCHER. How much had you increased your speed Sunday night?
Mr. PITMAN. To 21 1/2 knots.
Senator FLETCHER. What increase was that over the speed you had been making prior to that?
Mr. PITMAN. Only about a knot.
Senator FLETCHER. You had been making about 20 1/2?
Mr. PITMAN. Yes, 20 1/4 and 20 1/2 first, after we left Queenstown.
Senator FLETCHER. How long did that continue?
Mr. PITMAN. The next day, 21.

I have to assert that 20 1/4 or 20 1/2 is definitely less than 21 knots.

What conclusions can we take from this?

 

[Markus Philipp]

whether conditions?, I meant weather conditions.

 

[Jim Currie]

I am a bit confused.
Lord said in US enquiry, at 9.40 am. he was at 42-00 N 47-00 W, and at 10.21 pm. he was at 42-05 N, 50-7 W.
This works out 187 minutes of arc longitude according to 139 miles at 42° latitude.
The time elapsed is 12 hours 40 minutes. The speed is 139/12,67 = 11 knots (10.97). I exspected nothing else.
46-15 west is about 34 miles east of Corner. If Course is 240° then the distance to longitude 46-15 is just 39 miles. So Californian should have passed this longitude at somewhere 6 am and not at midnight.
Did I get something wrong?

Hello Markus.

No Markus, you didn't get it wrong, I did. I was copying from old notes on work I had done before when trying to determine the track of the SS Californian. Well spotted! Groves and Evans were indeed friends. Here's how my mind was working and where the mix-up came from

Lord said:

" 11064. Did you attempt to communicate with the vessel [bcolor=rgb(252, 252, 255)]Titanic[/bcolor] on Sunday? A: - Yes, sir.
11065. At what time of the day? A: - Ten minutes to 11.
11066. A. m.? A: - P. m.
11067. That is ship's time? A: - At the ship's time for 47º 25' longitude.
11068. (Senator Burton.) That was of longitude 47º 25' west? A: - Yes, sir."

The foregoing suggests that Californian was at 47-25' West, 42-02 'North at Noon on April. If so, then her clocks would be 1 Hour 50 minutes FAST of EST New York.
If Lord thought she was at The Corner at 9-40 am then 2 hours 20 minutes later, found her to be 18.6 miles west and 2 miles north of her intended course, then Californian must have encountered more or less the same conditions in that areas as did Titanic. i.e. she was set back and to the southward during the previous 12 hours. I suspect that her Chief Officer Stewart verified this by star observations about 4 hours earlier. I also suspect that he called Captain Lord when he had worked his sights and the captain altered course to the west, directly for The Corner. If I'm right, then she probably averaged 9.9 knots from 6 am to 9-40 am and made good a course of almost West. That being the case then between 6 am and 9-40 am she covered a distance of 36.3 miles. If she did, then at 6 pm when W/O Evans came on duty, she would have been at 46-11 West
and the difference between apparent time ship and EST New York would have been 1 hour 55 minutes.

 

[Markus Philipp]

If she did, then at 6 pm when W/O Evans came on duty, she would have been at 46-11 West
Do you mean 6 pm or 6 am? Why should the morning longitude matter for a message in the evening?

I would think it that way:

9.40 am Corner, 47-00 West, DR based on morning observations
noon Position unknown, intended 47-25 West, based on calculations the day before.
10.21 pm stopped at 50-07 West, DR based on evening observations.
Distance and speed between these two: 139 miles, 12 hours 40 minutes, 11 knots.

The precalculated noon longitude 47-25 would be passed at 9.40 + 1 h 41 = 11.21 am, 39 minutes early.

( 25 minutes of arc equals 18,6 miles. Time to drive 18.6 miles at 11 knots: 1 h 41 minutes )

So he has to steam further 39 minutes to meet the sun.
This will take him 7 miles or 10 minutes of arc to west on longitude 47-35.
As ship's time is adjusted to 47-25 he will see the zenith of the sun 40 seconds past 12 o'clock ship's time.

39/60 hours * 11 knots = 7,15 miles corresponding to 9,62, round up 10 minutes of arc.

Result of noon observations:
He exspected to be at 47-25 west at 12 o'clock, but he found himself at 47-35 west at 12:00:40, seven miles further to west than exspected.

 

[Jim Currie]

Yes Markus, I meant am, not pm.

Evans actually came on Watch at 7 am. He was responsible for ensuring that all his transmissions and receipts during that day were accurately timed in terms of EST New York. Perhaps he decided that he would get his NYT at the beginning of each day? it is the only reasonable explanation for his 5 minute time difference from Captain Lord.

We can check Californian's navigation. Here is part of a Transcript of an interview with Captain Lord in 1961.

" Q70. And so far as that night is concerned, in summary, your navigation was being done in what you would call the normal way? A: Lord: In the normal way and in perfect conditions. The position was obtained at noon…
Q71. That would be a sun? A: Lord: Sun observation by three officers and myself. And the second officer took a, a dead-reckoning latitude and worked out the longitude about four o’clock in the afternoon, and gave it to me. It agreed by dead reckoning
The chief officer took the latitude by star about seven, between seven and eight that evening, and said that it agreed with dead reckoning. And we sent out our position at five, when we passed those three icebergs, giving our position. We sent our position out at noon, after observing, and broadcast it. And when we stopped that evening we sent out our position again, telling exactly where we stopped. "

With the understandable breaks in memory and continuity, the above is a perfect example of an every day set of concurrences aboard a Merchant Ship.

When he arrived at Boston, Captain Lord submitted the following report to the authorities:

"April 14, 6:30 P.M., latitude 42.05 N., longitude 49.10 W., sighted two large icebergs 5 miles south of the above position. At 7:15 P.M., latitude 42.05 N., longitude 49.20 W., two bergs, and 7:30 P.M. two bergs. At 10:20 P.M., latitude 42.05 N., longitude 50.07 W., encountered heavy packed field ice, extending north and south as far as the eye could see and about 5 miles wide; also numerous bergs could be seen."

In fact, the longitude for that first sighting was written on the original Marconigramm as 49-09'W

From the foregoing we can work back and forward from the longitude of the sighting of the icebergs at 6-30 pm.

The weather was perfect that day so 2nd Officer Stone would get a VG Longitude by chronometer at around 4 pm that afternoon. It follows that the DR Longitude for 6-30 pm local time ship for the sighting of the icebergs would be fairly accurate.

If Californian was at 47-25' West at Noon and 49-09' West 6.5 hours later, at 6-30 pm then she would have changed her longitude by 94 minutes and covered a distance of 69.9 miles in 6.5 hours, giving her an average speed from Noon of 10.75 knots. Her planned speed was 11 knots. This I would expect because very soon after Noon that day, Californian cleared the northern margin of the warm eastward setting current and at 4 pm. the sea temperature had dropped by a full 20 degrees F. from 56 F at Noon to 36 F.
Exactly the same thing happened with Titanic. As soon as she broke free of the current and the weather improved, her speed climbed dramatically .
As did Titanic's 4th Officer Boxhall, Captain Smith obviously thought that given the conditions, his ship would make 11.25 knots from 6-30 pm onward, Because the distance from the 6-30 position to his 10-20 pm stopped DR position is exactly 43.1 miles.

 

[Markus Philipp]

Yes Markus, I meant am, not pm.
"April 14, 6:30 P.M., latitude 42.05 N., longitude 49.10 W., sighted two large icebergs 5 miles south of the above position. At 7:15 P.M., latitude 42.05 N., longitude 49.20 W., two bergs, and 7:30 P.M. two bergs. At 10:20 P.M., latitude 42.05 N., longitude 50.07 W.,
In fact, the longitude for that first sighting was written on the original Marconigramm as 49-09'W

If Californian was at 47-25' West at Noon and 49-09' West 6.5 hours later, at 6-30 pm then she would have changed her longitude by 94 minutes and covered a distance of 69.9 miles in 6.5 hours, giving her an average speed from Noon of 10.75 knots. Her planned speed was 11 knots. This I would expect because very soon after Noon that day, Californian cleared the northern margin of the warm eastward setting current and at 4 pm. the sea temperature had dropped by a full 20 degrees F. from 56 F at Noon to 36 F.

I have got some objections:
1. If Californian was at 47-25' West at Noon ... Disagree. She was not at 47-25 at noon. She intended to be were, but she was fast.
If she would have been there at noon her speed from 47-00 at 9.40 til 47-25 at 12.00 would have been 8 knots only.

2. From 47-25' West at Noon to 49-09' the longitude increases 104 minutes, not 94.

3. Even if they got noon position by observation, we don't have evidence, we can only reconstruct by DR.

attached a scan of my Excel. There is a combination with 47-25 longitude reached at 11.23 am.
After 6.30 pm the Speed increases from 10.84 to 11.18 knots, but if you play with the time for noon longitude you can get whatever you like. So I am not really convinced.

Another Point: We misused already one thread for everything but original asked question. I would like this one to Focus on Titanic longitude time. There is a Pitman-Lightoller contradiction. I have got an idea how to solve that, but I would like you to add your ideas.

 

[Markus Philipp]

Back to Pitman's table
If ship's time was adjusted to precalculated noon longitude, as stated by Lightoller, the ship's time should have been altered by 1 h 23 minutes in the first night. (see remark at the end). The Speed calculated with 1 h 23 minutes would be 21 knots, but Pitman said:
Senator FLETCHER. You had been making about 20 1/2?
Mr. PITMAN. Yes, 20 1/4 and 20 1/2 first, after we left Queenstown.
In Pitman's table we find 59 minutes, which is definitely wrong.

484 miles 59 minutes 20,14 knots <--- wrong!
519 miles 44 minutes 21 knots
546 miles 44 minutes 22,1 knots

He put down this table from his memory. If the correct value to match with LAN would have been 1 h 23 minutes, one could understand that he took 1 h 20 or 1 h 25, but instead he gave us just 59 minutes.

1 h 23 minutes seems to be not correct as well. To achieve at 20,5 knots the clock alteration should be considerably more than 1 h 23 min.
Is it possible that the correct value was 1 h 59, and Pitman just missed the hour and put in the minutes only?
Let’s make a speed check for an assumed set back of 1 h 59 minutes:

Departure at Daunt Rock: 2.20 pm.
Elapsed time til Friday noon: 21 hours 40 minutes
Clock set back: 1 h 59 minutes, sum of elapsed time: 23 h 39 minutes
Speed calculated: 484/23,65 = 20,46 knots

20,46 knots! Now we get something between 20 ¼ and 20 ½.

Pitman’s table after correction, 1 h 59 minutes for the first night:

484 miles 1 h 59 minutes 20,44 knots
519 miles 44 minutes 21 knots
546 miles 44 minutes 22,1 knots

Remaining time to complete 5 hours: 1 h 33 minutes, sounds familiar? The ghost of Lightoller wawing here?

1 h 33 minutes can be split into 46 and 47 minutes. This would be the set back times for the next two days with an assumed speed of 21,5 knots.

Now I want to present my idea what they might have done. In Queenstown they made a precalculation of the whole journey with an assumed speed of 21 knots respectively 21,5 knots and found these times to set the clocks back:

484 miles 1 h 23 minutes 20,5 knots
520 miles 49 minutes 21 knots exspected
520 miles 44 minutes 21 knots exspected
532 miles 46 minutes 21,5 knots exspected
532 miles 47 minutes 21,5 knots exspected

Total mileage at Tuesday noon: 2588 miles
Left over time Tuesday noon: 31 minutes fast of EST
remaining distance til Ambrose: 302 miles (2890 - 2588)
time from Tuesday noon til Arrival at Ambrose: 14 hours (302 miles / 21,5 knots)
Arrival at Ambrose based on calculation above: 1.30 am

We know that they were steaming with 22 knots since Saturday noon, maybe they exspected something like that, therefore they took in account to arrive at Ambrose at Tuesday midnight or even before midnight. What they would have done at Ambrose I don’t know, stay at anchor or take a pilot and go on to Ellis Island. They found it inconvenient to alter the clocks at Tuesday evening or midnight, so they shifted the 31 minutes back into the first night.

Result: 1 h 54 minutes clock setback in the first night, 1 h 23 + 31 minutes
According Pitman’s table the clocks were altered by 44 minutes instead of 49 minutes. Why they did so I cannot say. But I take it as it is. We have 5 minutes more to be shifted in the first night. Thus we arrive at 1 h 59 minutes which the clocks were to set back in the first night.

This will set the ship’s time about 30 minutes aside of longitude time at noon. As consequence of that they had to take the noon observations at 11.30 ship's time.

I exspect now a big outcry, but if we want to factor Pitman’s testimony:
Senator FLETCHER. You had been making about 20 1/2?
Mr. PITMAN. Yes, 20 1/4 and 20 1/2 first, after we left Queenstown.
there is no other way than to put more than 1 h 23 minutes into the first night.

To meet the condition that noon position at Sunday 12 o clock ship’s time was 126 miles before the corner we have to follow that based on the observations at 11.30 they calculated the noon Position for 12 o clock ships’time.

The mileages 484, 519, 546 miles were calculated as difference between the positions at 12 o’clock ship’s time.

What Lightoller said, "The clocks are set at midnight, but that is for the approximate noon position of the following day. Therefore Sunday noon the clocks will be accurate" is the general rule.

But in this case this rule had caused inconvenience: The distance from Corner to Ambrose is 1215 miles. Steaming at 22 knots the remaining time is 55 hours, - 2 days 7 hours.
Estimated arrival at Ambrose: 6 pm (Corner) + 7 hours - 2 hours, 11 pm Tuesday night.
They would have to do an extraordinary clock set back before midnight.
To avoid this they shifted the final set back into the first night.

The key testimony for this:
Senator FLETCHER. You had been making about 20 1/2?
Mr. PITMAN. Yes, 20 1/4 and 20 1/2 first, after we left Queenstown.

This requires a setback of 2 hours in the first night.
59 minutes were found in Pitman's table, but obviously he meant 1 h 59 minutes.


Remark: clock set back the first night:
For my calculation I split the the great circuit into three rhumb lines, each 540 miles.
The first line starts at Fastnet Rock, 51-22 North 9-36 West and ends up at 49-39 North and 23-30 West.
The course is south 79° west.
484 miles - 55 miles (Roche's Point to Fastnet) equals 429 miles.
429 miles travelled on the first rhumb line ends at noon position 50-00 North 20-41 west.

Clock set back: 20,67 * 4 = 82,7 minutes, round up 83 minutes, 1 h 23 minutes.

 

[Samuel Halpern]

A lot to digest Markus. I need to spend more time on this, but the one comment I have about the Pitman table is that he made an obvious error when calculating the speed for the 1st day out. Using the time he gave in the memo, 22h 38m = 22.63 h divided into 484 miles is 21.4 knots. He wrote 20.14, inserting a 0 after the 2.

I'll have more to say at another time.

 

[Michael Kestner]

But in this case this rule had caused inconvenience: The distance from Corner to Ambrose is 1215 miles. Steaming at 22 knots the remaining time is 55 hours, - 2 days 7 hours.
Estimated arrival at Ambrose: 6 pm (Corner) + 7 hours - 2 hours, 11 pm Tuesday night.
They would have to do an extraordinary clock set back before midnight.
To avoid this they shifted the final set back into the first night.

My math agrees closely with yours. I think if Titanic had maintained her April 14 speed for the rest of the voyage she would have arrived at Ambrose at approximately 10:40pm Tuesday night. Where I don't follow (and maybe I'm just out of my depth here) is why they would add that extra 31 minutes to the first night instead of Tuesday night. What would be the point? Would that not throw their navigation out of whack for the rest of the voyage, since ships time would no longer match Local Apparent time?